New environmentally stable positive tone chemically amplified resist system - KRS

Abstract

It is known that one of the main shortcomings of chemically amplified resist systems is their sensitivity to airborne base contaminants. The contaminants cause unpredictable linewidth variations deeming the resist incompatible with manufacturing. Besides other issues, this drawback has greatly contributed to the slow introduction of DUV into manufacturing and discouraged most semiconductor manufactures from including DUV in their strategic plans. In this paper, we present a new positive tone chemically amplified photoresist system which is resilient to airborne base contaminants and it shows stable linewidth for more than 24 hours delay between exposure and development. This resist has high sensitivity (17-18 mj/cm2), high contrast (7), high resolution (0.35 μm with λ = 248 nm and NA = 0.37) and large process latitude in deep-UV lithography. This resist also exhibits high resolution (0.1 μm in 0.35 μm thick resist) in E-beam lithography at a sensitivity of about 10 μC/cm2. Both lithographic systems (deep-UV and E-beam) yield nearly vertical profiles in the resist images.